Answer :
D as the oxygen has gained to electrons from the magnesium in the reaction.
the answer is M2O
why?
the assumed valency of M should be 1+ ( because it reacts with oxygen and the valency is not provided)
the valency of oxygen is O2-
thus, by cris cross technique, we get M2O
why?
the assumed valency of M should be 1+ ( because it reacts with oxygen and the valency is not provided)
the valency of oxygen is O2-
thus, by cris cross technique, we get M2O